It appears as though one of the brain’s natural hormones spurs the burning of fat within the gut. This conclusion was reached by Scripps Research Institute (TSRI) biologists who relied on animal models for their studies. Their findings were recently published in Nature Communications and will serve to advance pharmaceutical development in years to come.
Details of the Study
The TSRI study was spearheaded by Professor Surpriya Srinivasan and Research Associate Lavinia Palamiuc. Though Srinivasan refers to the study as “basic science”, it certainly shed light on an intriguing mystery. Prior studies showed that the neurotransmitter serotonin has the potential to spur fat loss. However, no one was exactly sure as to how this phenomenon occurred.
Srinivasan’s team used roundworms known as “C. elegans” that are commonly employed as model organisms for biology purposes. Such worms have comparably simple metabolic systems when pitted against humans, yet their brains generate similar signaling molecules. This makes researchers believe the findings in C. elegans are meaningful for humans. The scientists eliminated genes within the C. elegans to determine if the pathway between brain serotonin and fat burning could be interrupted.
The researchers tested numerous genes to pinpoint one in which fat burning would not occur. This experiment led the crew to a gene that codes for FLP-7, a neuropeptide hormone commonly pronounced as “fip 7”. The mammalian version of this neuropeptide hormone was identified 80 years prior as a peptide that spurred muscle contractions when placed on pig intestines. Scientists of yesteryear believed this hormone linked the brain and the gut yet no one connected the neuropeptide to the metabolism of fat in the years since.
The Study’s Second Part
The second step of the study centered on the determination of whether FLP-7 had a direct connection to the brain’s serotonin levels. A fluorescent red protein was added to FLP-7 in order to visualize it in living animals. The results showed that FLP-7 was released from the brain’s neurons as a response to heightened levels of serotonin. FLP-7 moved through the circulatory system and initiated the burning of fat within the gut. This finding is noteworthy as it’s the first time researchers pinpointed a brain hormone that selectively spurs the metabolism of fat without impacting food intake.
How the Fat-Metabolizing Pathway Functions
Here is how the fat-metabolizing route works: One of the brain’s neural circuits generates serotonin as a result of sensory cues like the availability of food. This triggers another neuron set to launch the production of FLP-7 which spurs a receptor within intestinal cells. The intestines then convert fat into energy.
The TSRI team proceeded to study the consequences of altering FLP-7 levels. Though bumping up serotonin levels can affect an animal’s food intake, reproductive behavior and movement in a number of ways, researchers determined that boosting FLP-7 levels farther downstream did not produce any clear side effects. The worms used in the study functioned as expected while metabolizing more fat. Srinivasan stated that this critically important finding will likely influence ensuing studies regarding how FLP-7 levels can be regulated without producing the side effects that occur when serotonin levels are altered.
